cask audit: check for sourceforge appcast

Library/Homebrew/cask/lib/hbc/audit.rb

@@ -34,7 +34,7 @@ module Hbc
       check_single_pre_postflight
       check_single_uninstall_zap
       check_untrusted_pkg
-      check_github_releases_appcast
+      check_hosting_with_appcast
       check_latest_with_appcast
       check_stanza_requires_uninstall
       self
@@ -246,13 +246,25 @@ module Hbc
       add_warning "Casks with an appcast should not use version :latest"
     end
 
-    def check_github_releases_appcast
+    def check_hosting_with_appcast
       return if cask.appcast
+      check_github_releases_appcast
+      check_sourceforge_appcast
+    end
+
+    def check_github_releases_appcast
       return unless cask.url.to_s =~ %r{github.com/([^/]+)/([^/]+)/releases/download/(\S+)}
 
       add_warning "Cask uses GitHub releases, please add an appcast. See https://github.com/Homebrew/homebrew-cask/blob/master/doc/cask_language_reference/stanzas/appcast.md"
     end
 
+    def check_sourceforge_appcast
+      return if cask.version.latest?
+      return unless cask.url.to_s =~ %r{sourceforge.net/(\S+)}
+
+      add_warning "Cask hosted on SourceForge, please add an appcast. See https://github.com/Homebrew/homebrew-cask/blob/master/doc/cask_language_reference/stanzas/appcast.md"
+    end
+
     def check_url
       return unless cask.url
       check_download_url_format

Library/Homebrew/test/cask/audit_spec.rb

@@ -460,6 +460,28 @@ describe Hbc::Audit, :cask do
       end
     end
 
+    describe "SourceForge appcast check" do
+      let(:error_msg) { /Cask hosted on SourceForge/ }
+
+      context "when the Cask is not hosted on SourceForge" do
+        let(:cask_token) { "basic-cask" }
+
+        it { is_expected.not_to warn_with(error_msg) }
+      end
+
+      context "when the Cask is hosted on SourceForge and has an appcast" do
+        let(:cask_token) { "sourceforge-with-appcast" }
+
+        it { is_expected.not_to warn_with(error_msg) }
+      end
+
+      context "when the Cask is hosted on SourceForge and does not have an appcast" do
+        let(:cask_token) { "sourceforge-correct-url-format" }
+
+        it { is_expected.to warn_with(error_msg) }
+      end
+    end
+
     describe "latest with appcast checks" do
       let(:error_msg) { "Casks with an appcast should not use version :latest" }
 

Library/Homebrew/test/support/fixtures/cask/Casks/sourceforge-with-appcast.rb

@@ -0,0 +1,8 @@
+cask 'sourceforge-with-appcast' do
+  version '1.2.3'
+
+  url 'https://downloads.sourceforge.net/something/Something-1.2.3.dmg'
+  appcast 'https://sourceforge.net/projects/something/rss',
+          checkpoint: '407fb59baa4b9eb7651d9243b89c30b7481590947ef78bd5a4c24f5810f56531'
+  homepage 'https://sourceforge.net/projects/something/'
+end